Along with the progress of technology, computer has become part of our daily life, and therefore I/O devices, such as mouse and keyboard, are improved as well to be more user friendly. The usage of the mouse is more than the keyboard except for typewriting, and there are two types of mouse in the market, which are mechanical mouse and optical mouse. The mechanical mouse uses a ball and related sensors to detect the position of the mouse, and has characteristics of lower technical skill, lower cost, but it is ease to carry and accumulate dust inside the internal thereof while the ball is rolling that will eventually affect the normal operation of the same. On the other hand, optical mice using light to detect the position of the mice will have no such problem. However, it has a structure more complicate than the mechanical one and thus has a higher manufacturing cost. Referring to FIG. 1, which is an exploded view of an optical mouse according to prior arts. The optical mouse currently sold in the market comprises: a case body 11, a control circuit 12, and an optical system 13, wherein the optical structure 13 further comprises a light emitting diode (LED) 131, an LED assembly clip 132, a lens mount 133, a sensor 134 and a digital processor (not shown). Typically, the optical mouse uses the LED 131 for illuminating a surface, such as a mouse pad or surface of a table. The light strikes the surface and a portion of light is reflected to generate patterns of different size. The sensor 134 will then record the reflected light. Based on the reflected light, the digital processor determines the movement and direction of the mouse.
In view of the above description, it is noted that the accuracy of the positional information derived from the reflected light is dependent on the quality of the light emitted from the LED 131. In a convention optical mouse as seen in FIG. 1, the LED assembly clip 132 fixes the LED 131 onto the control circuit 12 corresponding to the positioning holes 121 for arranging the LED 131 at the lens mount 133 and enabling the axis of the light emitted by LED 131 to be coaxial with that of the lens mount 133 so as to completely bring the illumination light generated by the LED 131 into full play. In this regard, the precise installation of the LED 131, the LED assembly clip 132 and the lens mount 133 on the exact positions corresponding to the positioning holes 121 can ensure the optical mouse to operate accurately.
However, the optical structure of prior arts may need to be advanced while in application. For instance, the LED assembly clip 132, the positioning holes 121 and the lens mount 133 formed separately not only increase the difficulty of manufacturing the same, but also increase the cost. Moreover, the conventional optical mouse has problem to position the devices therein properly and precisely, in addition, its complex structure induces high manufacturing cost and increase difficulty of mass-production such that the quality and the cost can not be controlled and enhanced.
The devices used in the prior art for fixing the LED 131, such as the LED assembly clip 132 and the positioning holes 121 on control circuit 12, are parallel to the working surface of the optical mouse such that the lens mount 133 receiving the light emitted from the LED 131 can not collimate the same onto the working surface. In view of the description above, the U.S. Pat. No. 6,476,970, “Illumination Optics and Method”, submitted by George Edward Smith, filed on Aug. 10, 2000, combines the lens mount 133 and a prism 135 to collimate illumination light onto a working surface 14 by reflecting the same twice as seen in FIG. 2. However, according to the Snell Law, light is lost during every reflection, and therefore the additional prism 135 not only increases the manufacturing cost of lens mount 133, but also more light will be lost during reflection.
Moreover, referring to FIG. 1, a means for fixing the LED 131 and the LED assembly clip 132 is to have a positioning structure with a pair of upper and lower half-arcs or right and left half-arcs arranged on the case body 11 to fasten LED 131. It is hardly to avoid the dropping of the mouse due to careless operation that causes the axis of the light emitted by LED 131 to shift by the vibration and therefore the axis of the light emitted by LED 131 is not perpendicular to a central line of an optical system of the optical mouse, and consequently, the sensor 134 can not record a clear and uniform image by which the digital processor can not determines the movement and direction of the mouse accurately.
Other and further features, advantages and benefits of the invention will become apparent in the following description taken in conjunction with the following drawings. It is to be understood that the foregoing general description and following detailed description are exemplary and explanatory but are not to be restrictive of the invention. The accompanying drawings are incorporated in and constitute a part of this application and, together with the description, serve to explain the principles of the invention in general terms. Like numerals refer to like parts throughout the disclosure.